# Sandbox SDK adds file permission control

By Steven Van · 2026-03-20

Version 1.9.0 lets writeFiles set a mode like 0o755, skipping a separate chmod call when creating executable scripts.

The [Vercel](<https://creatorstoolbox.com/tools/vercel>) Sandbox SDK can now set file permissions while writing a file, instead of writing it and then running chmod as a separate step. Version **1.9.0** adds a mode property to the writeFiles API, so a script can be created and made executable in one call, such as mode: 0o755 for run.sh. See the [SDK reference](<https://vercel.com/docs/vercel-sandbox/sdk-reference>) for details.

[![](<https://vercel.com/api/docs-og?title=JS%20SDK%20Reference&format=docs&sig=64faa92449ae0b9c480511c142e2f90fbb77bd4f7c053df84f7846f42096ba9b&category=Run%20agents%20and%20backends&subcategory=Sandbox>)](<https://vercel.com/docs/vercel-sandbox/sdk-reference>)

![Vercel](<https://www.google.com/s2/favicons?domain=vercel.com&sz=128>)

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Sources

[Original source](<https://vercel.com/docs/vercel-sandbox/sdk-reference>)

[Read Sandbox SDK adds file permission control on Creators Toolbox](<https://creatorstoolbox.com/blog/vercel-sandbox-sdk-adds-file-permission-control>)

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Canonical source: https://creatorstoolbox.com/blog/vercel-sandbox-sdk-adds-file-permission-control